The max volume of the Internal Volume control is the current System Volume setting. Do you just mean increasing the System Volume?
If so, you can set MC to always max out the System Volume when playing, which means then Internal Volume corresponds to the full possible range of your audio device. This is best for audio quality as well.
Or, do you mean overdriving your audio device above 0.0dB? This is not recommended for any digital volume control as it will introduce distortion. You'd be better off to use MC's Dynamic Volume system to compress the audio if needed (for night playback or cruddy laptop speakers). If needed, though, both EQ DSPs can raise audio levels like a pre-amp. Again, though, if you go over 0.0dB, it'll clip and distort.